Various types of impact sensors have been proposed in order to trigger safety devices to protect passengers in vehicles, typically automobiles. Some of those sensors, as previously proposed, use a spring element and a mass secured to the spring element, the mass being deflected upon impact against the spring force. Deflection of the mass against the spring force closes electrical contacts. Such contacts, of course, are used only infrequently--desirably never--but when they are operated, they must operate reliably. Long disuse of the contacts within the operating life of the vehicle; may cause operating problems when they are actually needed.